A conventional cable distribution system uses a head-end center to broadcast media content to a plurality of client devices via a cable distribution network. The cable distribution network can be implemented as a coaxial cable network or as a combination of fiber-optic and coaxial cable networks. This hybrid solution is referred to as a Hybrid Fiber Coax (HFC) system.
In one well known approach, the cable system broadcasts media content (such as television programs) over a plurality of channels. In the case of digital channels, the head-end center commonly uses quadrature amplitude modulation (QAM) to modulate media content for transmission over the cable network. More specifically, the head-end center can multiplex together a plurality of digital channels into a single transport stream and then convey these channels over a QAM signal on a 6 MHz carrier.
A client device in a cable system may include a cable set-top box for receiving and processing the media content. The set-top box supplies processed media content to a television set for output to a user. In operation, a user generates a channel tune event in conventional fashion, e.g., by selecting a channel with a remote control device. In response, the set-top box uses a tuner to selectively extract desired media content from one of the channels. The tuner performs this task by adjusting a bandpass filter such that content delivered over an identified frequency is selectively extracted from a received broadcast signal.
A conventional satellite system uses a similar approach to broadcast media content to set-top boxes. In this approach, a satellite distribution infrastructure is used to supply broadcast media content to set-top boxes. The set-top boxes extract desired channels from the broadcast media content by using a physical tuning mechanism in the manner described above.
The market has also recently seen the emergence of Internet Protocol (IP) based systems for delivering media content. According to one such system, one or more servers can be used to deliver media content to a plurality of client devices over an Internet-Protocol (IP) network. The client devices can comprise IP-enabled set-top boxes. Instead of a physical tuner that uses a bandpass filter, an IP set-top box includes a virtual tuner. The virtual tuner accesses a stream of digital content by specifying an address associated with a server-side source of the media content. Compared to traditional broadcast solutions, IP-based systems can offer more targeted content to individual IP set-top boxes, that is, by enabling dedicated one-to-one transmission of media content to individual set-top boxes.
While IP-based solutions may be superior to conventional cable and satellite broadcast systems in some respects, the industry has invested a significant amount of financial resources in this type of traditional technology. Accordingly, simply abandoning traditional systems in favor of IP-based solutions may not be a feasible option.